The LV123A devices are dual retriggerable Monostable Multivibrators designed for 2-V to 5.5-V VCC operation.
These edge-triggered multivibrators feature output pulse-duration control by three methods. In the first method,
the A input is low and the B input goes high. In the second method, the B input is high and the A input goes low.
In the third method, the A input is low, the B input is high, and the clear (CLR) input goes high.
The output pulse duration is programmable by selecting external resistance and capacitance values. The
external Timing capacitor must be connected between Cext and Rext/Cext (positive) and an external resistor
connected between Rext/Cext and VCC. To obtain variable pulse durations, connect an external variable
resistance between Rext/Cext and VCC. The output pulse duration also CAN be reduced by taking CLR low.
Pulse triggering occurs at a particular voltage level and is not directly related to the transition time of the input
pulse. The A, B, and CLR inputs have Schmitt Triggers with sufficient hysteresis to handle slow input transition
rates with jitter-free triggering at the outputs.
Once triggered, the basic pulse duration CAN be extended by retriggering the gated low-level-active (A) or
high-level-active (B) input. Pulse duration CAN be reduced by taking CLR low. The input/output Timing diagram
illustrates pulse control by retriggering the inputs and early clearing. By Texas Instruments